Atwood furnace won't stay lit

[endothermic_biped]

Greetings, all.
I'm looking for a little bit of guidance on an issue I'm having. We've got a trailer with an Atwood furnace...AFMD30 I think it is. The furnace will ignite but won't stay lit. The blink codes on the control board indicate failure to detect the flame. I'd have to agree with the little blinkey light...I hear it ignite but I can also hear the igniter never stops trying to ignite. I'm pretty sure it's a defective control board. When I opened the access panel to the furnace the board was wet...several of the components on top are rusted/corroded, etc. In addition, it was working fine just a few months ago. I can just buy a board but most electronic components aren't returnable so I'm trying to verify the flame sensor. I found a youtube video with the guy using a capacitor and ammeter and I'm not afraid of doing that but capacitors are harder to come by since the Radio Shack closed its doors. So is that the only way to test the flame sensor? Or should I just quit worrying about it and get the control board?

Thanks in advance...

[SeaDog]

I think the first thing I would do is take some emery cloth and clean the flame sensor then retry. Being an old HVAC guy I have done this many times on household furnaces.

[jeff64]

Originally Posted by SeaDog

I think the first thing I would do is take some emery cloth and clean the flame sensor then retry. Being an old HVAC guy I have done this many times on household furnaces.

X2 seen this before as well. Flame presence sensor = ignitor! Sends a feedback to the board. I like brass brush myself but shouldn't make a difference. Clean off mounting connections and hardware at the same time. You can get a .pdf on line for the furnasty and pay attention to any install, inspection of electrode, clearance or orientation instruction on that igniter. Ya'd think as long as it sparks and lights the gas you'd be good...not necessarily so!

[endothermic_biped]

Thanks. I'll give it a try. Weather and work have kept me from fiddling with it. Hope to work on it tomorrow. It's just over a year old and we've only used the heat on maybe three trips so I wouldn't figure the flame sensor would be fouled with carbon yet but I'll definitely give it a look. If it wasn't so far to our dealer I'd just get it fixed under warranty but as it is it'll cost me more in diesel fuel to get to the dealer than it will to just buy a board (or flame sensor). I'll post the fix when I find it.

[endothermic_biped]

Well, for what it's worth...my trouble turned out to be a defective control board. Since it is so new I skipped checking on the flame sensor. Instead I checked the current between the flame sensor and board. I was getting about 6 microamps so I replaced the board and I've got heat again.

[SeaDog]

glad you got it fixed thanks for the pic I see what you were talking about.